J L Melo

The Brazilian spherical detector: progress and plans

We are building the Schenberg gravitational wave detector at the Physics Institute of the University of Sao Paulo as programmed by the Brazilian Graviton Project. The antenna and its vibration isolation system are already built, and we have made a first cryogenic run for an overall test, in which we measured the antenna mechanical Q (figure of merit). We also have built a 10.21 GHz oscillator with phase noise performance better than -120 dBc at 3.2 kHz to pump an initial CuA16% two-mode transducer. We plan to prepare this spherical antenna for a first operational run at 4.2 K with a single transducer and an initial target sensitivity of h ∼ 2 x 10 -21 Hz -1/2 in a 50 Hz bandwidth around 3.2 kHz soon. Here we present details of this plan and some recent results of the development of this project.

The Brazilian gravitational wave detector Mario Schenberg : status report

The Mario Schenberg gravitational wave detector has been constructed at its site in the Physics Institute of the University of Sao Paulo as programmed by the Brazilian Graviton Project, under the full support of FAPESP (the Sao Paulo State Foundation for Research Support). We are preparing it for a first commissioning run of the spherical antenna at 4.2 K with three parametric transducers and an initial target sensitivity of h ~ 2 × 10−21 Hz−1/2 in a 60 Hz bandwidth around 3.2 kHz. Here we present the status of this project.

The Brazilian gravitational wave detector Mario Schenberg: progress and plans

The Schenberg gravitational wave detector is almost completed for operation at its site in the Physics Institute of the University of Sao Paulo, under the full support of FAPESP (the Sao Paulo State Foundation for Research Support). We have been working on the development of a transducer system, which will be installed after the arrival of all the microwave components and the completion of the transducer mechanical parts. The initial plan is to operate a CuAl6% two-mode parametric transducer in a first operational run at 4.2 K with nine transducers and an initial target sensitivity of h ~ 2 × 10−21 Hz−1/2 in a 50 Hz bandwidth around 3.2 kHz. Here we present details of this plan and some recent results of the development of this project.

The status of the Brazilian spherical detector

The first phase of the Brazilian Graviton Project is the construction and operation of the gravitational wave detector Mario Schenberg at the Physics Institute of the University of S?o Paulo. This gravitational wave spherical antenna is planned to feature a sensitivity better than h = 10?21 Hz?1/2 at the 3.0?3.4 kHz bandwidth, and to work not only as a detector, but also as a testbed for the development of new technologies. Here we present the status of this detector.

The gravitational wave detector "Mario Schenberg": status of the project

The first phase of the Brazilian Graviton Project is the construction and operation of the gravitational wave detector Mario Schenberg at the Physics Institute of the University of Sao Paulo. This gravitational wave spherical antenna is planned to feature a sensitivity better than h = 10-21 Hz-1/2 at the 3.0-3.4 kHz bandwidth, and to work not only as a detector, but also as a testbed for the development of new technologies. Here we present the status of this detector.

Overall mechanical transfer function calculated for a spherical resonant gravitational waves antenna

In this article, we describe the vibrational isolation system, the thermal link and the transducer mechanical structure, for the Schenberg resonant gravitational wave detector, which has been conceived modeled and analyzed using the finite element method. The dynamical equations corresponding to the structure have been solved using the MSC/NASTRAN software. In order to study the overall system behavior and the noise influence on it, we have carried out the analysis considering simultaneously all mechanical systems: vibrational isolation, thermal linking (between the dilution refrigerator and the suspension), and transducer-resonant mass mechanical coupling. Our calculation shows that a 300 dB attenuation level could be obtained.

Vibration isolation support system for a truncated icosahedral gravitational wave antenna

We designed a mechanical isolation system for an icosahedral resonant gravitational wave detector we plan to construct in Brazil. We have used the NASTRAN finite element software to perform the numerical analysis. Our results show that the designed system could allow a damping factor better than −200 dB in the spectral range of interest, which is adequate to the sensibility level we want for the antenna.

Vibration isolation support design for the SCHENBERG detector

We designed a mechanical isolation system for a spherical resonant gravitational wave detector we are building in Brazil. We have used the finite element method to perform the dynamical analysis. The system is a multiple stage passive pendulum formed by cylinders joined by C springs and rods. Our results showed that the designed system could allow a 280 dB attenuation factor in the bandwidth, from 3.1 to 3.2 kHz, where the SCHENBERG detector will be sensitive.

The antenna–transducer mechanical coupling design for the Schenberg detector

We are designing microwave parametric transducers to be used in the Brazilian gravitational wave detector. In this paper, we explain the technical constraints used to design the mechanical parts of these transducers. The transducer and the antenna have been modelled by a finite element model (FEM) and the corresponding dynamical equations have been solved using the Msc/Nastran software. We have used the FEM analysis results in an iterative way, adjusting the geometric parameters in each step. Using this procedure we were able to calculate the transducer mechanical structure by positioning its main resonance frequency to the value of the spheres quadrupolar mode frequency in order to design the best possible mechanical coupling and increasing transducer efficiency.

The first phase of the Brazilian graviton project: The Mário Schenberg detector

The construction of a CuAl (94%–6%) 0.6-meter diameter truncated icosahedral gravitational wave antenna is currently being proposed in Brazil. The system is planned to feature a sensitivity better than h=10−21 Hz−1/2 at both (4.10.4) kHz and (7.90.8) kHz bandwiths.